Liquid fuel burning device

ABSTRACT

A liquid fuel burning device comprising a wick for sucking and burning a liquid fuel contained in a fuel tank by capillarity and a vent passage which is provided in a portion other than a fuel passage used by the wick and allows communication between an interior of the fuel tank and the outside air at least during combustion.

TECHNICAL FIELD

This invention relates to the structure of a lighter or other liquidfuel burner that uses an alcohol fuel or the like and is equipped with awick for drawing up and burning a liquid fuel.

In particular, this invention relates to a wick peripheral structure forobtaining a desired burning state in a burner (e.g., a cigarettelighter, torch, lantern or other such fire-lighting device, lamp or thelike) that uses a liquid fuel such as an alcohol, a benzine hydrocarbonor a petroleum hydrocarbon.

BACKGROUND TECHNOLOGY

An alcohol fuel such as ethyl alcohol, a benzine fuel of the petroleumbenzine type or a liquid gas fuel such as butane gas or propane gas isgenerally used as the fuel of a cigarette lighter, fire-lighting device,torch, lamp or other such burner.

The performance, ease of use, and structural design of such burnersdiffers depending on the kind of fuel used, and each has its owncharacteristics. In the case of a liquid gas fuel, for instance, the gaspressure is high in the use temperature range of the burner and thevessel storing the fuel has to have a pressure-resistant structure.Moreover, the flame length changes with variation in the gas pressureand since it is a characteristic of the gas pressure to varylogarithmically and greatly with temperature, large change in flamelength with temperature becomes a particular problem. In order to reducethis flame-length variation, the fuel supply mechanism of the burnerrequires a special design countermeasure for effecting temperaturecompensation, which complicates the structure and is disadvantageousfrom the aspect of cost.

In contrast, since a liquid fuel such as an alcohol fuel is a liquid atordinary temperatures and is also relatively low in vapor pressure, itdoes not require a pressure-resistant vessel in the fuel storage sectionand, as such, simplifies the structure of the burner and is advantageousfrom the aspect of cost. Further, in the liquid fuel burner, the meansused to supply the liquid fuel from the fuel storage section to theflame-producing section is generally a wick that utilizes the surfacetension of the liquid fuel to draw it up through continuous fine holesor fine voids among bundled fibers by capillarity and burns it at thetip portion thereof.

Specifically, the wick used for drawing up the fuel is a string-like oneobtained by twisting fibers, one obtained by bundling fibers, one usingboth of these with the glass fibers enclosed in cotton yarn and theresult interwoven with fine metal wires to prevent disintegration, orthe like, whose the lower end portion functions to draw up fuel to beburned at the upper end tip portion.

However, the burner using such a wick has problems in that the liquidfuel leaks through the wick owing to the difference between the internalpressure of the fuel tank retaining the liquid fuel and the externalpressure and that a phenomenon of drawing in external air arises.

Specifically, after draw-up and combustion of the alcohol or otherliquid fuel by the wick has been initiated by lighting (igniting) theliquid fuel at the wick, liquid fuel is consumed at the flame-producingsection at the tip of the wick and liquid fuel for maintaining thecombustion is drawn up from the fuel tank and supplied to theflame-producing section. The flame length varies until an equilibrium isreached between the amount of liquid fuel consumed at theflame-producing section and the amount of fuel drawn up from the tankand supplied to the flame-producing section.

When the burner is a fire-lighting device such as a cigarette lighter,the flame is preferably stabilized at the set flame length as quickly aspossible after ignition. For this, the draw-up section of the wickshould preferably have the maximum possible liquid fuel draw-upcapacity, while attention must also be given to preventing occurrence ofa pressure differential between the fuel tank and the external air toensure that the outflow of the liquid fuel from the fuel tank does notproduce a reduced pressure state that hinders draw-up through thedraw-up section of the wick.

On the other hand, as regards the opposite case of a high pressurearising in the fuel tank, attention must be given to ensuring thatliquid fuel stored in the fuel tank does not leak to the exteriorthrough fuel passages formed by the wick, particularly to ensure thatliquid fuel leakage does not occur in a pocketable fire-lighting deviceor the like.

Thus, when a difference arises between the internal pressure of the fueltank and the external pressure owing to the aforesaid depletion of fuelwith use or to a change in the surrounding temperature or the ambientpressure, the liquid fuel burner is liable to become inconvenient touse, i.e., to experience leakage of liquid fuel through the wick whenthe internal pressure of the fuel tank becomes high and to experiencelighting (ignition) failure when the fuel tank internal pressure becomesso low as to allow external air to be sucked in through the wick.

Moreover, suppression of evaporative dispersion of liquid fuel from thewick of a burner using one of the aforesaid wicks is important forincreasing service life (number of uses), while it is also preferable tomake the overall configuration compact.

Vaporization from the wick is prevented by covering the wick portionalone or the whole upper surface portion including the wick with a capto seal the wick and suppress vaporization during non-use periods.Completely reliable sealing is, however, hard to achieve. This isparticularly true when covering is effected by causing the cap to swingalong an upward arc, because the need to provide the seal portion inconformity with the locus of rotation results in increased spacingbetween the wick and other components such as the igniter, making itdifficult to secure sealing property and compact configuration.

Particularly when a striker wheel is used for the igniter, separationbetween the wick and the striker wheel degrades igniting performance andlowers the reliability of the product.

In view of these circumstances, the invention is directed to providing aliquid fuel burner enabling rapid elimination of pressure differencebetween the interior and exterior of the fuel tank.

DISCLOSURE OF THE INVENTION

This invention overcomes the foregoing problems by providing a liquidfuel burner comprising a wick for burning liquid fuel drawn uptherethrough by capillarity from a fuel tank, characterized in that itis provided at a location apart from fuel passages of the wick with anair passage communicating the interior of the fuel tank with externalair at least during burning.

Since the invention liquid fuel burner uses liquid fuel as a matteroperating principle, it does not need a pressure-resistant structure ora valve system and can therefore be of simplified structure. Moreover,the invention enables low-cost mass production of a burner exhibitingstable burning characteristics with minimal change in flame length withtemperature change. Owing to the provision of the air passagecommunicating the interior of the fuel tank with the exterior air at alocation apart from the fuel passages of the wick, moreover, decrease infuel tank internal pressure with depletion of the liquid fuel in thefuel tank is offset by inflow of external air through the air passage,thereby eliminating pressure difference between the interior andexterior of the fuel tank. After the flame-producing section of the wickhas been lit, therefore, an amount of liquid fuel equal to thatcontained in the wick and consumed by burning can be quickly replenishedwith liquid fuel from the fuel tank through the fuel passages of thedraw-up section, which is not in a reduced pressure state. The fuelsupply response is therefore improved to provide a stable burning stateimmediately after lighting.

Another aspect of the invention provides a liquid fuel burner comprisinga wick for burning liquid fuel drawn up therethrough by capillarity froma fuel tank, characterized in that the wick is divided into two segmentsat least one of which is movable to contact and separate from the other,fuel being supplied from one segment to the other during contact andfuel supply being cut off during separation to limit burning period, andan air passage communicating the interior of the fuel tank with externalair at least during burning is provided at a location apart from fuelpassages of the wick.

Since separation of the segments cuts off the supply of fuel, a functionof automatic extinguishment after a prescribed period of burning can beeasily obtained with high reliability. Owing to the provision of the airpassage communicating the interior of the fuel tank with the exteriorair at a location apart from the fuel passages of the wick, pressuredifference between the interior and exterior of the fuel tank can berapidly eliminated to further enhance the reliability and stability ofthe burning period limiting function.

The liquid fuel burner according to the invention can comprise a closurecap for preventing fuel vaporization. This provides a sealing effectthat suppresses evaporative dispersion of liquid fuel from the wick andthe air passage and thereby extends the service life.

When an openable/closable anti-vaporization closure cap for sealing thewick flame-producing section is provided, the opening of the air passageto the external air is preferably formed to communicate with the spacesealed by the closure cap in its closed state or to be closed by thesealing end of the closure cap in its closed state. Alternatively, anair passage closure member can be provided on the closure cap or gangedtherewith to open/close the opening of the air passage to the externalair simultaneously with the operation of the closure cap to open/closethe flame-producing section of the wick. By such means, when the closurecap is in the closed state the air passage is also closed to effectprevention of liquid fuel vaporization, while during use with theclosure cap open, the air passage is also opened to produce an effect ofequilibrating the internal pressure of the fuel tank and the externalpressure.

The air passage can be constituted as a gap along a wick holder providedto surround the outer periphery of the wick or as a groove formed in theinner surface of the wick holder. In can also be constituted bydisposing a capillary tube along the wick or as a groove formed in thewick. Since such an air passage situated near the wick enables rapidelimination of pressure differentials between the fuel tank interior andexterior produced by changes in the ambient temperature or ambientpressure of the burner, leakage of liquid fuel and intake of externalair through the fuel passages in the wick can be reliably prevented toforestall inconvenience during use.

Another aspect of the invention provides a liquid fuel burnercharacterized in comprising a wick provided on an upper wall portion ofa fuel tank for holding liquid fuel and adapted to burn liquid fueldrawn up therethrough by capillarity from the fuel tank, an igniter forlighting the wick, an air passage communicating the interior of the fueltank with external air at least during burning provided at a locationapart from fuel passages of the wick, a cap for sealing an upper end ofthe fuel tank from which the wick and the igniter protrude by traversinga straight path along the direction of wick protrusion to fit over andcover the upper end of the fuel tank from above, and an O-ring, packingor other such seal member interposed at a sealing portion of the cap.

With this configuration, the cap can seal the upper end of the fuel tankfrom which the wick and the igniter protrude by traversing a straightpath along the direction of wick protrusion to fit over and cover theupper end of the fuel tank from above. Since this simplifies the sealstructure and offers a high degree of freedom regarding componentspacing, it enables a more compact structure.

The cap can be internally equipped with an inner cap that is operated inunison with an operation for attaching/detaching the cap to/from thefuel tank to seal the wick through an interposed seal member. Since thisconfiguration reduces the volume of the sealed space, it exhibits anexcellent liquid fuel vaporization suppressing effect.

When the cap is internally provided with the inner cap, the inner cap ispreferably guided to seal the wick by a peripheral fitting portionbetween the fuel tank and the cap during attachment/detachment of thecap to/from the fuel tank. This configuration enables good performanceof the attachment/detachment operation with respect to the internalfitting portion, thereby facilitating securement of reliable sealing.

The inner cap can be attached to the cap through an elastic member thatenables sealing of the wick with the seal member maintained underpressure. Since this configuration lowers the degree of dimensionalprecision required during fabrication, it facilitates production.Preferably in this configuration, either the inner cap is disposedeccentrically relative to the cap and a surface orthogonal to adirection of attachment/detachment at the peripheral fitting portion ofthe cap and the fuel tank is shaped to have radial asymmetricdirectionality or the inner cap is disposed concentrically relative tothe cap and a surface orthogonal to the direction ofattachment/detachment at the peripheral fitting portion of the cap andthe fuel tank is shaped to have radial symmetry. This configurationimproves ease of use by enabling ready attachment in accordance with theshape of the cap without need for attention to the position of the innercap.

The risk of dropping or losing the cap can be eliminated by providing aconnecting member for connecting the fuel tank with the cap detachedtherefrom.

The upper end of the fuel tank to which the cap is detachably attachedcan be provided about at least part of its outer periphery with anupwardly projecting peripheral wall. This peripheral wall can be formedwith an inclined upper edge or be provided with air holes to serve as awindshield, and can also function as a guide member for the cap.

The cap can be provided with a guide member for slidingly guiding it inthe attachment/detachment direction relative to the fuel tank and can befurther made movable to a retracted position not over the wick and theigniter after it has moved to or beyond a position where it disengagesfrom the fuel tank. This configuration improves the cap opening andclosing operability while ensuring good sealing and compact size.

The guide member can be constituted as a shaft member for guiding thecap in the attachment/detachment direction relative to the fuel tank toa position where a lower end of the cap is higher than tip portions ofthe wick and the igniter, the shaft member be connected to the cap at apoint apart from its center, and the cap be adapted to rotate to theretracted position about the shaft member. As another configuration, theguide member can be provided midway with a hinge and the cap can be mademovable to the retracted position by swinging it in an upward arc aboutthe hinge. These configurations are particularly superior in the pointthat the cap does not become a hindrance during ignition and use.Energizing means is preferably providing for biasing the cap from theslid position on the guide member to the retracted position.

When the cap seals the upper end of the fuel tank from which the wickand the igniter protrude by traversing a straight path along thedirection of wick protrusion to fit over and cover the upper end of thefuel tank from above, the wick can be divided into two segments at leastone of which is movable to contact and separate from the other, fuelbeing supplied from one segment to the other during contact and fuelsupply being cut off during separation.

As the liquid fuel there can be used an alcohol fuel, for example, onehaving a lower monovalent alcohol, namely, methyl alcohol, ethyl alcoholor propyl alcohol, as its main component and having mixed therewith asaturated hydrocarbon such as hexane or heptane for coloring the flame,or, otherwise, a benzine hydrocarbon or a petroleum hydrocarbon or thelike.

As the wick there can be used one whose flame-producing section anddraw-up section are formed of different materials as in the embodimentsset out below or, otherwise, one whose flame-producing section anddraw-up section are integrally formed of the same material.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of a lighter as an example of aliquid fuel burner that is a first embodiment of the invention.

FIG. 2 is a schematic sectional view of a lighter that is a secondembodiment.

FIG. 3 is a sectional view of an essential portion of a lighter that isa third embodiment.

FIG. 4 is a sectional view of an essential portion of a lighter that isa fourth embodiment.

FIG. 5 is a sectional view taken along line A—A in FIG. 4.

FIG. 6 is a sectional view of an essential portion of a lighter that isa fifth embodiment.

FIG. 7 is a sectional view taken along line B—B in FIG. 6.

FIG. 8 is a sectional view of an essential portion of a lighter that isa sixth embodiment.

FIG. 9 is a sectional view taken along line C—C in FIG. 8.

FIG. 10 is a sectional view of an essential portion of a lighter that isa seventh embodiment.

FIG. 11 is a sectional view taken along line D—D in FIG. 10.

FIG. 12 is a sectional view of an essential portion of a lighter that isan eighth embodiment.

FIG. 13 is a sectional view of an essential portion of a lighter that isa ninth embodiment.

FIG. 14 is a sectional view taken along line E—E in FIG. 13.

FIG. 15 is a sectional view of an essential portion of a lighter that isa tenth embodiment.

FIG. 16 is a sectional view of an essential portion of a lighter that isan eleventh embodiment.

FIG. 17 is a sectional view of an essential portion of a lighter that isa twelfth embodiment.

FIG. 18 is a sectional view of an essential portion of a lighter that isa thirteenth embodiment.

FIG. 19 is a schematic sectional view of a lighter that is a fourteenthembodiment.

FIG. 20 is a plan view of the lighter of FIG. 19 with the cap detached.

FIG. 21 is a schematic sectional view of a lighter that is a fifteenthembodiment.

FIG. 22 is a plan view of the lighter of FIG. 21 with the cap detached.

FIG. 23 is a sectional view of an essential portion of a lighter that isa sixteenth embodiment.

FIG. 24 shows a plan view of a lighter that is a seventeenth embodimentwith the cap detached and a sectional view of an essential portionthereof.

FIGS. 25A and 25B show plan views of two types of lighters according toan eighteenth embodiment with the caps detached.

FIG. 26 is a sectional view of an essential portion of a lighter that isa nineteenth embodiment.

FIG. 27 is a perspective view of an essential portion of a lighter thatis a twentieth embodiment.

FIG. 28 is a sectional view of an essential portion of FIG. 27.

FIG. 29 is a sectional view of an essential portion of a lighter that isa twenty-first embodiment.

FIGS. 30A and 30B show sectional views of the essential portion of alighter that is a twenty-second embodiment, with the cap attached anddetached.

FIGS. 31A-31B are set of graphs showing how flame length varied as afunction of post-ignition burning period at different air passagediameters.

FIG. 32 is a graph showing how flame length immediately after ignitionvaried as a function of air passage diameter.

FIG. 33 is a graph showing how time for flame length to reach 25 mmvaried as a function of air passage diameter.

FIG. 34 is a graph showing how stable state flame length varied as afunction of air passage diameter.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the liquid fuel burner according to the invention will beexplained in the following with reference to the drawings.

<First Embodiment>

FIG. 1 schematically shows the sectional structure of a disposablecigarette lighter as an example of a liquid fuel burner.

The lighter, designated by reference numeral 1, has a fuel tank 2 ofcylindrical shape with closed bottom. Fiber material 3 (stuffing) isinserted into the interior of the fuel tank 2 and a top cover 4 is fixedto the upper portion of the fuel tank 2 to constitute a sealed structurethat contains, but cannot be refilled with, liquid fuel.

The fuel tank 2 is, for example, provided as a shaped article made ofpolypropylene with an inner volume of 5 cm³. The fiber material 3 ispolypropylene fiber of a thickness of 1-2 denier compacted in the fueltank 2 to a density of 0.1 g/cm³. 4 g of liquid fuel, a mixture of 95 wt% ethyl alcohol and 5 wt % n-hexane, is poured and impregnated into thisfiber material 3 for storage therein.

A wick 6 retained by a wick holder 7 is installed to pass verticallythrough the top cover 4 into the fuel tank 2. The wick 6 is formedseparately of different materials at an upper flame-producing section 61and a lower draw-up section 62 and the two are joined by the cylindricalmetal wick holder 7 with the lower end portion of the flame-producingsection 61 and the upper end portion of the draw-up section 62 in acontacted state.

The wick holder 7, which is provided on its outer periphery with afastening thread 7 a, is screwed into a threaded hole 4 a of the topcover 4 of the fuel tank 2 to sandwich a seal ring 8 at the bottom andbe fixed in place. A face plate 9 is provided on the upper surface ofthe top cover 4.

The lower end portion of the draw-up section 62 of the wick 6 contactsthe fiber material 3 in the fuel tank 2 and draws up the liquid fuelimpregnated in the fiber material 3 utilizing capillarity. Theflame-producing section 61 of the wick 6 is lit to burn and generate aflame.

The flame-producing section 61 is composed of bundled glass fibers. Forexample, glass fibers having a thickness of 6 μm, a fiber density(metsuke amount) of 150 mg/cm³, an outer diameter of 3 mm and a lengthof 10 mm are inserted into the wick holder 7 to protrude to a length of3 mm from the tip portion of the wick holder 7.

The draw-up section 62, formed as a rod having a large-diameter headportion by molding and sintering polyethylene powder, has its headportion inserted into the lower portion of the wick holder 7 to makecontact with the lower end of the flame-producing section 61, and thelower end portion of the wick holder 7 is caulked in this state, wherebythe flame-producing section 61 and the draw-up section 62 are integrallyjoined to constitute the wick 6.

The draw-up section 62 is, for example, obtained by placing in a moldpolyethylene powder that is a mixture of particles of 70-200 mesh withan average particle size of 140 mesh and sintering it for 10 minutes at170° C. The head portion 62 a is formed to an outer diameter of 4.2 mmand a length of 3 mm and the lower leg portion to an outer diameter of 4mm and a length of 37 mm.

The amount of fuel consumed by the wick 6 when lit, the flame shape andthe flame length are determined by the thickness, number and length ofthe glass fibers of the flame-producing section 61. In contrast, theformation pattern of the gaps in the draw-up section 62, whichdetermines the fuel draw-up and supply characteristics, differs with thethickness, the particle diameter of the sintered polyethylene, thesintered density and the like of the draw-up section 62. The headportion of the draw-up section 62, being formed to a large diameter tohave a large volume, constitutes a fuel reservoir for holding the liquidfuel. Burning stabilization is obtained by this fuel reservoir.

An igniter 10 is installed on the top cover 4 to face the tip of theflame-producing section 61 of the wick 6. A bracket 11 of the igniter 10fixed to the top cover 4 has a flint 12 inserted therein to bevertically movable and a rotating striker wheel 13 is provided on theupper end of the bracket 11. The tip of the flint 12 is pressed onto theperipheral surface of the rotating striker wheel 13 by the force of aflint pusher spring 14 and rotation of the rotating striker wheel 13causes sparks to fly toward the wick 6.

A closure cap 16 for evaporation prevention is provided toopenably/closably cover the flame-producing section 61 of the wick 6together with the protruding portion of the wick holder 7. This closurecap 16 is rotatably pivoted by a pin 17 at one end portion of the uppersurface of the top cover 4 of the fuel tank 2. The closure cap 16 isformed to have an internal U-shaped sealed space S and the sealing endfor pressure contact is provided with a seal member 18.

An air passage 20 is opened in the lighter 1 of the foregoing structureby boring a hole through the top cover 4 and the face plate 9 tocommunicate the interior of the fuel tank 2 with the external air. Theopening of the air passage 20 on the external air side is situated at apoint inward of the seal member 18 of the closed closure cap 16 so as tocommunicate with the sealed space S. The diameter of the air passage 20is, for example, 0.5 mm-2.0 mm.

The presence of the air passage 20 enables the interior space of thefuel tank 2 to communicate with the external air while the closure cap16 is open. When the tip of the wick 6 is lit by the igniter 10 andburning commences, liquid fuel is supplied from the draw-up section 62to the flame-producing section 61 through the fuel passages of the wick6 in an amount equal to the amount consumed at the flame-producingsection 61 by the burning. Liquid fuel is thus successively drawn upfrom the fuel tank 2. Ordinarily the reduction in the internal pressureof the fuel tank 2 this produces owing to the diminishing volume of theliquid fuel in the fuel tank 2 tends to impede fuel draw-up. However,since any pressure differential that arises is eliminated by aproportional inflow of external air through the air passage 20,unimpeded, rapid supply of fuel to the flame-producing section 61 can beobtained to ensure prompt stabilization of the flame length from theinitial burning stage.

When the internal pressure of the fuel tank 2 rises above the externalair pressure because of, for instance, an increase in the temperature ofthe lighter 1 or a decrease in the external air pressure, internal airis discharged through the air passage 20. Therefore, liquid fuelretained in the wick 6 does not leak out through the flame-producingsection 61. Conversely, when the internal pressure of the fuel tank 2falls below the external air pressure because of, for instance, adecrease in the temperature of the lighter 1 or an increase in theexternal air pressure, external air flows in through the air passage 20.Since liquid fuel retained in the wick 6 is therefore not forced back byinflowing external air, no fuel deficiency arises at the flame-producingsection 61.

When the closure cap 16 is shut, escape of vaporized liquid fuel throughthe air passage 20 is suppressed because the exterior opening of the airpassage 20 communicates with the sealed space S.

The lighter 1 according to the First Embodiment was subjected to testsunder use conditions to ascertain the effect of forming the air passage20. The results are set out in a later section.

<Second Embodiment>

As shown in FIG. 2, the lighter 1 of this embodiment resembles thepreceding embodiment in the configuration of the wick 6 but differstherefrom in the relationship between the air passage 20 and the closurecap 16.

In this embodiment, the sealing end of the closure cap 16 has a sealmember 19 providing a broad seal surface and the air passage 20 is boredso that its exterior opening faces the seal member 19. In other words,the air passage 20 communicating the interior of the fuel tank 2 withthe external air is provided to be directly opened and closed inconjunction with the opening and closing operation of the closure cap16. The other portions are formed like those of the First Embodiment.The same constituent elements are assigned the same references symbolsand explanation thereof is omitted.

Like the First Embodiment, this embodiment also exhibits stable burningcharacteristics, while still more reliably preventing leakage of liquidfuel and vaporization through the air passage 20 when the closure cap 16is shut.

<Third Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 3. An air passage 21 communicating the interior of thefuel tank 2 and the external air is formed through in the wick holder 7fitted around the wick 6, so as run parallel to the wick 6.

An O-ring 31 for sealing is fitted around the tip portion of the wickholder 7 and sealing of the flame-producing section 61 of the wick 6 andthe opening of the air passage 21 is established by pressure contactbetween the inner peripheral surface of a sealing end 16 a of theclosure cap 16 and the O-ring 31. The sealing end 16 a of the closurecap 16 is beveled for easy fitting over the O-ring 31.

<Fourth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 4. A sectional view taken along line A—A of FIG. 4 isshown in FIG. 5. An air passage 22 communicating the interior of thefuel tank 2 with the exterior is formed by cutting away a portion of thewick 6 to establish a groove-like space between the wick 6 and the wickholder 7.

The flame-producing section 63 of the wick 6 of this embodiment is notmade of glass fibers but is a porous ceramic sintered body formed inround rod-like shape and contains continuous bubbles (capillarypassages) inside. The upper portion of this flame-producing section 63is mounted to protrude from the tip of the wick holder 7 by a prescribedamount (e.g., 3 mm). This protrusion amount, the diameter and the likedetermine the size of the flame. For instance, it is constituted to havean outer diameter of 3.0 mm and a length of 10 mm.

On the other hand, the draw-up section 62 whose tip portion abuts on thelower end portion of the flame-producing section 63 is again a porousmaterial made of a sintered body of polyethylene powder and formed intoround rod-like shape. An edge portion of the draw-up section 62 isremoved in the sectional shape of a circle segment from the tip portionof the flame-producing section 63 to a point below the wick holder 7 soas to form the air passage 22 between the wick 6 and the inner surfaceof the cylindrical wick holder 7. The characteristics of this airpassage are the same as those of the preceding embodiments.

<Fifth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 6. A sectional view taken along line B—B of FIG. 6 isshown in FIG. 7. Air passages 23 communicating the interior of the fueltank 2 with the exterior are formed by spaces between the wick 6 and thewick holder 7.

Specifically, the flame-producing section 61 and the upper portion ofdraw-up section 62 of the wick 6 are formed to have circularcross-sections and the inner hole 7 b of the wick holder 7 is formed tohave a rectangular cross-section. Approximately triangular spaces aretherefore defined to pass vertically at the four corners between thetwo. These spaces constitute the air passages 23 communicating theinterior of the fuel tank 2 with the exterior. The other portions areformed like those of the Third Embodiment.

<Sixth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 8. A sectional view taken along line C—C of FIG. 8 isshown in FIG. 9. An air passage 24 communicating the interior of thefuel tank 2 with the exterior is formed by a groove provided in theinner hole 71 a of a wick holder 71.

Specifically, a portion of the inner surface of the inner hole 71 a ofthe wick holder 71 for holding the wick 6 is formed with a verticalgroove extending over the full length of the wick holder 71 in the axialdirection. When the wick 6 is inserted into the inner hole 71 a, the airpassage 24 is defined to run parallel to the peripheral surface of thewick 6. The inner hole 71 a for holding the wick 6 is formedeccentrically in the wick holder 71 and the air passage 24 is providedin the thick wall portion. The other portions are formed like those ofthe Third Embodiment.

<Seventh Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 10. A sectional view taken along line D—D of FIG. 10 isshown in FIG. 11. An air passage 25 communicating the interior of thefuel tank 2 with the exterior is formed by a groove provided between thewick holder 7 and the top cover 4 of the fuel tank 2.

Specifically, a threaded hole 4 a is formed through the top cover 4 ofthe fuel tank 2 and a fastening thread 7 a formed at the lowerperipheral portion of the wick holder 7 for holding the wick 6 thereinis screwed into the threaded hole 4 a. A portion of the inner surface ofthe threaded hole 4 a is formed over its full length with a verticalgroove. The air passage 25 communicating the fuel tank 2 with theexterior is constituted by this vertical groove. The other portions areformed like those of the First Embodiment.

<Eighth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 12. An air passage 26 communicating the interior of thefuel tank 2 with the exterior is formed by a vertical groove provided inthe outer periphery of the wick holder 7.

Specifically, a portion of the fastening thread 7 a cut around lower endof the wick holder 7 is formed with a vertical groove to a lengthgreater than the thickness of the top cover 4 of the fuel tank 2 so asto define the air passage 26 between the inner and outer sides of thetop cover 4. The other portions are formed like those of the SeventhEmbodiment.

<Ninth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 13. A sectional view taken along line E—E of FIG. 13 isshown in FIG. 14. An air passage 27 communicating the interior of thefuel tank 2 with the exterior is formed by a capillary tube installedparallel to the wick 6.

Specifically, a capillary tube 32 is implanted vertically at the side ofand in parallel with the inner hole 71 a of the wick holder 71 of thewick 6. The inner channel of the capillary tube 32 constitutes the airpassage 27. The inner hole 71 a for holding the wick 6 is formedeccentrically in the wick holder 71 and the air passage 27 is providedin the thick wall portion. The other portions are formed like those ofthe Third Embodiment.

<Tenth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 15. In this embodiment the wick 6 is divided into twosegments to enable rationed burning.

The wick 6 is divided into two segments by splitting the draw-up section62 into a lower draw-up segment 62 b and an upper draw-up segment 62 awhich is capable of sliding vertically together with the glass fiberflame-producing section 61 to bring its lower end into and out ofcontact with the upper end of the lower draw-up segment 62 b.Specifically, the flame-producing section 61 and the upper draw-upsegment 62 a are retained in a cylindrical wick holder 72 and the wickholder 72 is supported in a slide hole 4 b in the top cover 4 of thefuel tank 2 to be vertically slidable. On the other hand, the lowerdraw-up segment 62 b has its upper end fixed to the top cover 4 and itslower end inserted into the fuel tank 2. The upper draw-up segment 62 aconstitutes a fuel reservoir of a volume capable of retaining thequantity of fuel required for a prescribed period of burning at theflame-producing section 61.

An air passage 28 communicating the interior of the fuel tank 2 with theexternal air is formed of a first air passage segment 28 a passingvertically through the wick holder 72 and a second air passage segment28 b formed to pass through the floor of the slide hole 4 b of the topcover 4 to communicate with the first air passage segment 28 a.

The wick holder 72 is fitted with a seal ring 33 and accommodated in theslide hole 4 b and is biased in the separating direction (upward) by acoil spring 34. The coil spring 34 is inserted between the upper surfaceof the top cover 4 and the upper end of the wick holder 72. When theflame-producing section 61 and the upper draw-up segment 62 a moveupward under the force of the coil spring 34, the lower end of the upperdraw-up segment 62 a separates from the upper end of the lower draw-upsegment 62 b to form a gap between the two segments.

A seal member 18 at the sealing end of an openable/closable closure cap16 for covering the flame-producing section 61 of the wick 6 is adaptedto press the wick holder 72 down by striking on its upper end at aregion outward of the opening of the first air passage segment 28 a.When the closure cap 16 is shut, it presses the wick holder 72 downwardagainst the force of the coil spring 34 to bring the lower end of theupper draw-up segment 62 a into contact with the upper end of the lowerdraw-up segment 62 b and simultaneously covers and seals the air passage28 of the flame-producing section 61 to prevent escape of vaporizedliquid fuel.

Since the upper draw-up segment 62 a and the lower draw-up segment 62 bof the wick 6 are thus in contact when the closure cap 16 is closed, aprescribed amount of liquid fuel is supplied to and retained by theflame-producing section 61. When the closure cap 16 is thereafteropened, the wick holder 72 is freed from the downward pressure and movedupward by the coil spring 34 to break the contact with the lower draw-upsegment 62 b and cut off the supply of fuel.

After the flame-producing section 61 is lit, the flame burns utilizingthe fuel retained in the flame-producing section 61 and the upperdraw-up segment 62 a. When all of the fuel has been used up, the flamegoes out automatically. The foregoing configuration thus constitutes arationed burning mechanism (automatic extinguishment mechanism). Thecharacteristics imparted by formation of the air passage 28 are the sameas those of the First Embodiment.

In this embodiment the draw-up segment 62 a and the lower draw-upsegment 62 b are formed to have inclined abutting surfaces so as toenlarge the contact area and increase the amount of liquid fuel suppliedper unit time.

<Eleventh Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 16. As in the Tenth Embodiment, the wick 6 is divided intotwo segments to enable rationed burning. An air passage 29 communicatingthe interior of the fuel tank 2 with the exterior is formed by cuttingaway a portion of the wick 6 to establish a groove-like space betweenthe wick 6 and the wick holder 72.

The structures of the flame-producing section 63 and draw-up section 62of the wick 6 and of the air passage 29 are the same as those in theFourth Embodiment.

The wick 6 is formed in a rod-like shape of a flame-producing section 63constituted of a porous ceramic sintered body, an upper draw-up segment62 a constituted of a sintered body of polyethylene powder, and a lowerdraw-up segment 62 b. Edge portions of the upper draw-up segment 62 aand the lower draw-up segment 62 b are removed in the sectional shape ofa circle segment (see FIG. 5) from the tip portion of theflame-producing section 63 so as to form the air passage 29 between thewick 6 and the inner surface of the cylindrical wick holder 72. Thecharacteristics of this air passage are the same as those of thepreceding embodiments.

<Twelfth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 17. The wick 6 and the air passage 20 are configured likethose of the Second Embodiment.

The closure cap 16 of this embodiment is formed to have an internalU-shaped sealed space S for openably/closably covering theflame-producing section 61 of the wick 6 together with the protrudingportion of the wick holder 7 and the sealing end thereof is providedwith a seal member 18, as in the configuration of the First Embodiment.

The closure cap 16 is further provided with a separate air passageclosure member 35 facing the opening of the air passage 20. The tip ofthe closure member 35 is provided with a seal member 35 a and theexterior opening of the air passage 20 is directly opened and closed inconjunction with the opening and closing operation of the closure cap16. The other portions are formed like those of the First Embodiment.

<Thirteenth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 18. Another structure for ganging the opening/closing ofthe air passage 20 with the opening/closing operation of the closure cap16 is illustrated.

An air passage closure member 37 consisting of a valve body is providedat the exterior opening of an air passage 20 formed through the topcover 4 for opening and closing this opening. The closure member 37 isbiased in the closing direction by a spring 38.

On the other hand, the closure cap 16 is formed with a protrudingpresser 36 capable of applying pressure to the closure member 37. Thestructure thus gangs the closing operation of the air passage closuremember 37 with the closing operation of the closure cap 16.

<Fourteenth Embodiment>

FIG. 19 schematically shows the sectional structure of a disposablecigarette lighter as an example of a liquid fuel burner. FIG. 20 is aplan view with the cap detached.

The wick 6 is integrally formed as, for example, a porous glass sinteredbody, a porous ceramic sintered body, or a porous material obtained bybundling glass fibers into a rod. As pointed out earlier, it can beformed separately of different materials at the upper flame-producingsection and the lower draw-up section.

An evaporation-preventing closure cap 16 for sealing the projectingupper ends of wick 6 and the igniter 10 is provided to beattachable/detachable with respect to the top cover 4 of the fuel tank2. To effect sealing, the cap 16 traverses a straight path along thedirection of wick 6 protrusion, i.e., moves in an attachment/detachmentdirection parallel to the longitudinal direction of the fuel tank 2 andthe axial direction of the wick 6, to fit over and cover the peripheryof the upper wall portion 4 from above.

The cap 16 is cylindrical and the inner periphery of its open lower endfits over the outer periphery of the upper end of the top cover 4 tosandwich a seal member 30 (an O-ring) provided on the top cover 4therebetween. The inner periphery of the lower end of the cap 16 istapered for easy fitting.

An air passage 20 is provided to pass vertically through the top cover 4of the fuel tank 2.

The cap 16 is retained in the closed state relative to the fuel tank 2by the sliding friction between the seal member 30 fitted on the topcover 4 and the inner fitting surface of the cap 16. Other retainingstructures can also be configured by adopting a different seal memberand appropriate design modifications. For instance, the seal member canbe a ring-shaped packing disposed at the outer peripheral portion of thefuel tank 2 contacted by the cap 16 in the axial direction, fittingportions of the outer surface of the top cover 4 and the inner surfaceof the cap 16 can be provided with a ridge-valley engagement structureas shown, for example, in FIG. 23 described later, and the cap 16 can beretained in a sealed state with pressure applied to a seal member(packing) at its tip portion.

When the cap 16 of this lighter 1 is removed from the fuel tank 2 bypulling it in the attachment/detachment direction, the wick 6 and theigniter 10 are exposed and the igniter 10 can be operated to generatesparks and light the tip of the wick 6. At extinguishment, the flame isblown out and the cap 16 is then fitted onto the fuel tank 2 in theaxial direction to seal the wick 6 and suppress escape of vaporizedliquid fuel.

<Fifteenth Embodiment>

This embodiment of the lighter 1 is shown in FIGS. 21 and 22.

The cap 115 of this embodiment is composed of a cylindrical main portionand a cylindrical inner cap 116 provided inside the main portion to sealonly the portion of the wick 6. As in the Fourteenth Embodiment, thewick 6 retained by the wick holder 7 is inserted vertically at thecenter of the top cover 4 of the fuel tank 2. A sea) member (O-ring) 31is fitted around the tip portion of the wick holder 7.

The inner cap 116 is disposed at the central portion of the cap 115 tobe concentric with the peripheral cylindrical portion thereof. When thecap 115 is fitted over the top cover 4 of the fuel tank 2 from abovetraversing a straight path in the attachment/detachment directionparallel to the direction of protrusion of the wick 6, the inner cap 116can be fitted over the outer surface of the wick holder 7 with the sealmember 31 interposed therebetween. The inner periphery of the lower endof the inner cap 116 is tapered for easy fitting.

An air passage 20 is formed groove-like in the inner surface of the ofthe wick holder 7, similarly to the configuration of the SixthEmbodiment, and the opening thereof communicates with the internalsealed space of the inner cap 116 in the closed state.

Although the igniter 10 is mechanically the same as that of theFourteenth Embodiment, it is sized and positioned to be insertablebetween the outer wall portion of the cap 115 and the inner cap 116 whenthe cap 115 is attached. In line with this, a space permitting insertionof the inner cap 116 is formed between wick holder 7 of the wick 6 andthe igniter.

The configuration is such that, prior to the inner cap 116 being fittedover the wick holder 7, the outer wall portion of the cap 115 is guidedby the peripheral fitting portion at the outer surface of the top cover4 so that the fitting position is determined to enable easy and reliablefitting. Although the seal member 30 of FIG. 19 is not interposed at theperipheral fitting portion, it can be provided if necessary. The otherportions are formed like those of the Fourteenth Embodiment.

<Sixteenth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 23. The configuration of the inner cap 216 of the cap 215differs from that of the preceding embodiment.

The cap 215 of this embodiment is composed of a cylindrical main portionand the cylindrical inner cap 216 provided inside the main portion toseal only the portion of the wick 6. The inner cap 216 is installed tobe slidable in the axial direction and is biased by an elastic body 218.

Specifically, a guide cylinder 217 is provided on the ceiling of the cap215, and the inner cap 216, a small-diameter cylinder, is retained inthe guide cylinder 217 to be capable of axially projecting andretracting. The elastic body (coil spring) 218 is inserted in the guidecylinder 217 under compression so as to bias the inner cap 216 in theprojecting direction. A retaining structure is provided for preventingthe inner cap 216 from falling out of the guide cylinder 217.

A sealing structure between the inner cap 216 and the wick 6 isconstituted by installing a seal member (ring-shaped packing) 39 aroundthe wick holder 7 in contact with the upper surface of the top cover 4and allowing the force of the elastic body 218 to press the lower end ofthe inner cap 216 onto the end surface of the seal member 39.

A ridge-valley engagement structure formed at the fitting portionbetween the outer surface of the top cover 4 and the inner surface ofthe outer cylindrical portion of the cap 215 prevents the cap from beingdetached by the force of the elastic body 218. The other portions areformed like those of the Fifteenth Embodiment.

<Seventeenth Embodiment>

This embodiment of the lighter is shown in FIG. 24. The cap 315 of thisembodiment is directional regarding attachment. FIG. 24(A) shows thestructure of the top cover 4 of the fuel tank 2 in plan view, with thecap 315 detached. The peripheral fitting portion is elliptical(egg-shaped). Since this shape does not have radial symmetry, the cap315 is directional regarding attachment. In contrast, the fittingportions in the Fourteenth to Sixteenth Embodiments are circular, i.e.,radial symmetrical, and have no directionality regarding attachment.

The wick 6 is disposed eccentrically with respect to the elliptical topcover 4, i.e., is offset to one side from the center of the top cover 4of the fuel tank 2, thereby securing a large space for installing theigniter 10, whose rotating striker wheel 13 or the like may therefore beof large size. Matched to this, the inner cap 316 inside the cap 315 isalso disposed at an offset position. The other portions are formed likethose of the Fifteenth Embodiment.

<Eighteenth Embodiment>

FIGS. 25A and 25B show plan views of the structures of the top cover 4of the fuel tank 2 of two types of lighters according to thisembodiment, with the caps detached. The caps do not have directionalityregarding attachment.

The shape of the peripheral fitting portion (shape in a planeperpendicular to the attachment/detachment direction) in FIG. 25(A) isthat of a triangle with radial symmetry and the shape of the peripheralfitting portion in FIG. 25(B) is that of a quadrangle with radialsymmetry. The cap attached (not shown) is formed to have a triangular orquadrangular shape conforming to the shape of the fuel tank 2.

The wick 6 is disposed at the center of the triangular or quadrangulartop cover 4, i.e., at the center of the radially symmetrical profile ofthe top cover 4 of the fuel tank 2, and, in conformity with this, aninner cap is, like the inner cap 116 in FIG. 21, formed at a centerlocation inside the cap (not shown). Attachment is possible at positionswhere the fitting portion of the cap is radially symmetrical and thoughthe degree of freedom is lower than with a circular shape, the cap doesnot have directionality regarding attachment. The other portions areformed like those of the Fifteenth Embodiment.

<Nineteenth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 26. This lighter 1 has the same basic structure as theFifteenth Embodiment but is additionally provided with a structure forpreventing loss of the cap 115.

Specifically, the cap 115 is provided with a first retainer 41, the fueltank 2 is provided with a second retainer 42, and the retainers 41 and42 are lined by a connecting member 43 such as a chain. The otherportions are formed like those of the Fifteenth Embodiment.

<Twentieth Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 27. A sectional view of the structure is shown in FIG. 28.In this embodiment, the cap 115 can be rotated to a retracted positionafter detachment.

The wick 6 is located at the center of the fuel tank 2, the igniter 10is provided at the side of the wick 6, and, as in the FifteenthEmbodiment, the cap 115 is provided with the inner cap 116.

A guide member 45, constituted as a shaft member, is attached to aninterior portion of the so-structured cap 115 at an eccentric locationnear the peripheral wall. The lower portion of guide member 45 isinserted into an edge portion of the fuel tank 2 to be slidable in theattachment/detachment direction, i.e., in the vertical direction. Bythis, the cap 115 is supported to be movable along the guide member 45in the attachment/detachment direction and to be rotatable about theguide member 45.

Energizing means 46 (a torsion coil) is fit over the guide member 45.One end of the torsion coil 46 is fastened to the inner surface of thecap 115 and the other end thereof is fastened to the edge of the fueltank 2. The cap 115 is thus biased in the rotating direction and actedon by an upward biasing force.

At least a portion of the peripheral edge of the upper end of the fueltank 2 is formed with an upwardly projecting peripheral wall 47. Theperipheral wall 47 is formed to be low at the portion of the igniter 10and to be high in the vicinity of the wick 6. It is provided with airholes 47 a. The peripheral wall 47 serves the dual functions of awindshield and a guide for the cap 115 at the time of attachment anddetachment.

In this embodiment, when the cap 115 has been fitted on the fuel tank 2to seal the wick 6 with the inner cap 116, the energizing means 46 iswound in the twisting direction and compressively deformed in the axialdirection.

In the course of removing the cap 115 to use the lighter, the lower endof the inner cap 116 first rises out of engagement with the seal member31 of the wick holder 7. In this state, the position of the cap 115 issuch that it would collide with the tip portion of the wick 6 and theigniter 10 if rotated. This does not occur, however, because the cap 115is moved upward along the peripheral wall 47 by the force of theenergizing means 46 until out of the collision range. When the lower endof the cap 115 has risen above the tip of the wick 6 and the tip of theigniter 10, the torsional force of the energizing means 46 automaticallyrotates the cap 115 around the guide member 45 from its position abovethe fuel tank 2 to a retracted position. When the cap 115 is to beclosed after use, it is rotated in the opposite direction to position itabove the fuel tank 2 and is then pressed downward into engagement alongthe guide member 45.

This embodiment facilitates the operation of removing the cap 115 at thebeginning of use and also prevents loss of the cap 115.

Although this embodiment is provided with the energizing means (torsioncoil) 46 for automatically rotating the cap 115 to the retractedposition, it is instead possible adopt a configuration without theenergizing means, in which case the cap 115 is manually rotated to theretracted position. Further, instead of providing the guide member 45 tomove together with the cap 115 in the direction of attachment anddetachment, it is possible to adopt a configuration in which the cap 115is made slidable relative to a fixed guide member 45 or in which theguide member 45 is made plate-like and the member for slidinglysupporting it is made rotatable.

<Twenty-First Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIG. 29. While the preceding embodiment rotates the cap 115 toa retracted position, this embodiment is configured to tilt the cap 115into a retracted position by bending a guide member 49.

The guide member 49 is provided near the location where the cap 115 fitson the top cover 4 of the fuel tank 2 to guide the cap 115 in theattachment/detachment direction. It is constituted as a leaf springhaving an intermediate hinge 49 a. The cap 115 is attached to the guidemember 49 above the hinge 49 a. The portion of the guide member 49 belowthe hinge 49 a is retained on the fuel tank 2 to be vertically slidableby use of a retaining member 50. The guide member 49 also structurallyincludes energizing means for biasing the cap 115 to fall over in thebending direction in the course of swinging in an upward arc about thehinge 49 a. The other portions are formed like those of the TwentiethEmbodiment.

In this embodiment, when the cap 115 is raised from the closed state, itfirst separates from its engagement with the fuel tank 2 and, afterrising a certain distance to a position where it is out of the way ofthe igniter 10 etc., is automatically tilted and moved to the retractedposition by the force acting in the tilting direction about the hinge 49a of the guide member 49.

Alternatively, the energizing means can be omitted from the embodimentto provide a configuration requiring the cap 115 to be manually swungalong the upward arc.

<Twenty-Second Embodiment>

An essential structural feature of the lighter of this embodiment isshown in FIGS. 30A and 30B. In this embodiment the wick 6 is dividedinto two segments to enable rationed burning.

In a configuration similar to that of the Sixth Embodiment, an airpassage is formed by a groove provided in the inner hole of a wickholder 65. The materials of the flame-producing section 63 and thedraw-up section 62 of the wick 6 are like those of the EleventhEmbodiment. Use of other materials is also possible, however. Forinstance, a flame-producing section 63 made of glass fibers or of aporous glass sintered body is also suitable.

The wick holder 65 is inserted into the top cover 4 with a seal ring 66interposed therebetween. The lower end of the wick holder 65 rests on anelastic member 67 (a disk spring) supported on the upper surface of aholding member 64. The elastic member 67 biases wick holder 65 in theseparating direction (upward). When the flame-producing section 61 hasbeen moved upward by the force of the elastic member 67, the lower endof the flame-producing section 61 separates from the upper end of thedraw-up section 62 to form a gap between the two.

A seal member 70 is fixed on the tip portion of an inner cap 69 of anopenable/closable cap 68 for covering the flame-producing section 63 ofthe wick 6. The lower surface of the seal member 70 is adapted strike onthe upper surface of the wick holder 65 and press the wick holder 65downward. When the cap 68 is shut, it strikes on and presses the wickholder 65 downward against the force of the elastic member 67 to bringthe lower end of the flame-producing section 63 into contact with theupper end of the draw-up section 62 and simultaneously covers and sealsflame-producing section 63. A ridge-valley engagement structure isfurther provided between the inner peripheral surface of the cap 68 andthe outer peripheral surface of the top cover 4.

The gap produced between the flame-producing section 63 and the draw-upsection 62 at separation need only be large enough to break the contact.One of around 1 mm or even smaller is sufficient. The elastic member 67is not limited to a disk spring but can instead be any of various othertypes such as a rubber member, multiple small-diameter coil springs or alarge-diameter coil like that in the Tenth Embodiment.

Although the flame-producing section 63 is adapted to make and breakcontact in response to attachment and detachment of the cap 68 in theforegoing embodiment, it is alternatively possible to secure automaticextinguishment capability by mounting on the fuel tank 2 a screwmechanism, rubber mechanism or the like for vertically moving theflame-producing section 63, and providing an operation member foroperating this mechanism, whereby the flame-producing section 63 can bemoved for making and breaking of contact by an operation of the user.

The embodiments of the invention described in the foregoing enable theoperations for attaching and detaching the cap to be conducted along astraight path coinciding with the direction of protrusion of the wickfrom the fuel tank. In conformity with this movement, the sealstructures at the sealing portions can be simplified. Moreover, thelinear locus of the cap corresponding its movement along a straight pathreduces interference with other components and, as such, enables compactcomponent layout and simplifies design.

<Tests>

An invention lighter according to the First Embodiment and a comparisonlighter of the same structure except for omission of the air passagewere tested to ascertain the effect of forming the air passage.

(1) Change in flame length during continuous burning

The wicks of lighters formed with different diameter air passages werelit and the change in flame length during 120 seconds of continuousburning was measured. The results are shown in FIGS. 31A-31D. Theresults are shown in FIG. 31(A) for a lighter with an air passagediameter of 0 mm, i.e., the comparison lighter, and in FIGS. 31(B),31(C) and 31(D) for invention lighters with air passage diameters of 0.5mm, 1.0 mm and 2.0 mm, respectively.

FIG. 32 shows how the flame lengths immediately after ignition in themeasurement of FIGS. 31A-31D varied as a function of air passagediameter. It will be noted that the flame length immediately afterignition was 20 mm in the invention lighters having air passages ascompared with 15 mm in the comparison lighter having no air passage.

FIG. 33 shows how time for flame length to reach 25 mm varies as afunction of air passage diameter. It will be noted that the timerequired for the flame length to reach 25 mm was 5 seconds in the caseof the invention lighters as compared with 20 seconds in the case ofcomparison lighter.

FIG. 34 shows how stable state flame length varied as a function of airpassage diameter. While the flame length stabilized with in about 20-30seconds of burning following ignition, the flame length at this time was25 mm in the case of the comparison lighter with no air passage but was40 mm in the invention lighters provided with air passages.

The significance of the foregoing results will be considered. AlthoughFIGS. 31A-31D show the change in flame length measured during 120seconds of continuous burning, what is important in actual use of alighter is the flame length immediately after ignition or within aperiod of around 10-20 seconds after ignition. Considering this point inlight of FIGS. 32 and 33, it can be seen that the flame lengthimmediately after ignition of the lighter with no air passage was short,that provision of the air passage made the flame length longer, and thatapproximately the same results were obtained at different air passagediameters in the range of 0.5-2.0 mm. While each of the flames firstgrew with passage of time following ignition and then stabilized at acertain length, provision of the air passage enabled the flame to growrapidly to a length suitable for use.

Moreover, as can be seen from FIG. 34, the stabilized flame length aftera certain burning time was markedly longer in the lighters having theair passage than in the lighter without it. In other words, the maximumflame length at a given amount of protrusion of the flame-producingsection of the wick is increased by providing the air passage. Thismeans that the amount of wick protrusion can be reduced. Since the sizeof the sealing portion of the cap for preventing escape of vaporizedfuel from the wick can be reduced when the amount of protrusion issmaller, the lighter can be made more compact.

(2) Liquid fuel leakage

The wick portion was observed for leakage of liquid fuel when theambient temperature was varied. The results are shown in Table 1. Thewick portion was also observed for leakage of liquid fuel when theambient pressure was varied ±20% relative to atmospheric pressure. Theresults are shown in Table 2.

When the ambient temperature increased and when the ambient pressuredecreased, the comparison lighter with no fire-lighting deviceexperienced leakage of liquid fuel from the wick because the internalpressure of the fuel tank became higher than the external pressure,while the invention lighters did not experience such leakage because thepressure differential was eliminated through the air passages.

TABLE 1 Temp. change Air passage diameter (mm) (Base temp: 23° C.) 0 0.51.0 2.0 −20° C. ∘ ∘ ∘ ∘  0° C. ∘ ∘ ∘ ∘ +20° C. x ∘ ∘ ∘ +30° C. x ∘ ∘ ∘(∘: No leakage x: Leakage)

TABLE 2 Air pressure change (From atmospheric Air passage diameter (mm)pressure) 0 0.5 1.0 2.0 −20% x ∘ ∘ ∘ +20% ∘ ∘ ∘ ∘ (∘: No leakage x:Leakage)

The embodiments of the invention described in the foregoing thus provideburners using liquid fuel, particularly lighters and other fire-lightingdevices for starting fires, which, being provided with an air passagealong the fuel passage (wick) to communicate the interior of the fueltank with the exterior in order to make the flame length after ignitionas long as possible and increase the growth rate of the flame lengthafter ignition, achieve better results than a burner not provided withan air passage. In addition, the length of the wick for securing a givenflame length can be shortened and the length of the sealing cap forpreventing escape of vaporized fuel from the wick during non-use can betherefore be shortened to simplify device design, while, by alsoproviding the air passage inside this sealed portion, escape ofvaporized liquid fuel through the air passage can be prevented andoozing of liquid fuel with change in ambient temperature and ambient airpressure can also be prevented.

What is claimed is:
 1. A liquid fuel burner comprising: a fuel tankcontaining fuel to be burned and having a bottom wall and side wallsterminating in an upper perimeter and having a top wall spanning theupper perimeter of the side walls and having a portion with asubstantially planar surface extending normal to the side walls; a wickextending into the fuel tank through a first opening formed in andextending through the substantially planar surface portion of the topwall for burning liquid fuel drawn up therethrough by capillarity, anair passage communicating through a second opening formed in andextending through the substantially planar surface portion of the topwall which is separate from and laterally spaced from the first openingbetween an interior of the fuel tank and external air at least duringburning, and a cap movable between open and closed positions andattached to the fuel tank in both the open and closed positions, the caphaving an internal space and a seal at an open end of the capsurrounding an opening to the internal space, the seal engaging thesubstantially planar surface portion of the top wall in the closedposition of the cap to enclose the wick in the internal space and toseal the first and second openings from external air when the burner isnot in use.
 2. A liquid fuel burner comprising: a wick for burningliquid fuel drawn up therethrough by capillarity from a fuel tank, thewick being divided into two segments at least one of which is movable tocontact and separate from the other, fuel being supplied from onesegment to the other during contact and fuel supply being cut off duringseparation to limit burning period, a cap for sealingly enclosing thewick when the burner is not in use, means for separating the twosegments upon removal of the cap from the wick, and an air passagecommunicating an interior of the fuel tank with external air at leastduring burning.
 3. A liquid fuel burner according to claim 1 or 2wherein the cap is an openable/closable closure cap for preventing fuelvaporization by sealing a flame-producing section of the wick and theopening of the air passage to external air is formed to communicate withthe internal space sealed by the closure cap in its closed state.
 4. Aliquid fuel burner according to claim 1 or 2 wherein the cap is anopenable/closable cap for preventing fuel vaporization by sealing aflame-producing section of the wick and the opening of the air passageto external air is formed to be closed by the seal of the closure cap inits closed state.
 5. A liquid fuel burner according to claim 1 or 2wherein the cap is an openable/closable closure cap for preventing fuelvaporization by sealing a flame-producing section of the wick and an airpassage closure member provided on or ganged with the closure cap, theair passage closure member opening/closing an opening of the air passageto external air simultaneously with operation of the closure cap toopen/close the flame-producing section of the wick.
 6. A liquid fuelburner according to claim 1 or 2, characterized in that the air passageis constituted as a gap along a wick holder provided to surround theouter periphery of the wick or as a groove formed in an inner surface ofthe wick holder.
 7. A liquid fuel burner according to claim 1 or 2,characterized in that the air passage is constituted by a capillary tubeextending along the wick.
 8. A liquid fuel burner according to claim 1or 2, characterized in that the air passage is constituted as a groove.9. A disposable liquid fuel burner comprising: a fuel tank constitutedas a sealed structure charged with a fiber material and containing, butnot refillable with, liquid fuel and having a bottom wall, side wallsterminating in an upper perimeter and a top wall spanning the upperperimeter of the side walls and having a portion with a substantiallyplanar surface extending normal to the side walls with spaced first andsecond openings formed in and extending through the substantially planarsurface portion, a wick having one end which is a draw-up sectioninserted in the fuel tank through the first opening in the top wall tocontact the fiber material and draw up liquid fuel by capillarity andhaving another end which is a flame-producing section retained by a wickholder to project from the top of the fuel tank, an openable/closableclosure cap movable between open and closed positions and attached tothe fuel tank in both the open and closed positions, the cap having aninternal space and a seal at an open end of the cap surrounding anopening leading to the internal space, the seal engaging thesubstantially planar surface portion of the top wall in the closedposition of the cap to enclose the wick in the internal space andsealing at least the flame-producing section of the wick when the burneris not in use, an igniter installed near the flame-producing section ofthe wick for lighting the flame-producing section, and an air passageprovided by the second opening capable of communicating an interior andexterior of the fuel tank through a portion apart from fuel passages ofthe wick, the second opening being closed by the cap from the exteriorof the fuel tank when the cap is in the closed position.
 10. A liquidfuel burner comprising: a fuel tank for holding liquid fuel and havingside walls and an upper wall with a substantially planar surface portionextending normal to the side walls with spaced first and second openingsformed in and extending through the substantially planar surfaceportion; a wick extending through the first opening in the upper wallportion and adapted to burn liquid fuel drawn up therethrough, anigniter for lighting the wick extending through the upper wall of thefuel tank, an air passage provided by the second opening communicatingan interior of the fuel tank with external air at least during burningprovided at a location apart from fuel passages of the wick, a cap forsealing an upper end of the fuel tank from which the wick and theigniter protrude supported for sliding motion in a straight path along adirection of wick protrusion to fit over and cover the upper end of thefuel tank from above at one end of the straight path and being laterallymovable away from the upper end of the fuel tank at the other end of thestraight path, and a seal member interposed at a sealing portion of thecap to engage the substantially planar surface portion when the cap isat said one end of the straight path.
 11. A liquid fuel burner accordingto claim 10, characterized in that the seal member is interposed betweenan outer peripheral portion of the fuel tank and the cap.
 12. A liquidfuel burner according to claim 10, characterized in that the cap isinternally equipped with an inner cap that is operated in unison with anoperation for attaching/detaching the cap to/from the fuel tank to sealthe wick through an interposed seal member.
 13. A liquid fuel burneraccording to claim 12, characterized in that the inner cap of the cap isguided to seal the wick by a peripheral fitting portion between the fueltank and the cap during attachment/detachment of the cap to/from thefuel tank.
 14. A liquid fuel burner according to claim 12 or 13,characterized in that the inner cap is attached to the cap through anelastic member that enables sealing of the wick with the seal membermaintained under pressure.
 15. A liquid fuel burner according to claim12 or 13, characterized in that the inner cap is disposed eccentricallyrelative to the cap and a surface orthogonal to a direction ofattachment/detachment at a peripheral fitting portion of the cap and thefuel tank is shaped to have radial asymmetric directionality.
 16. Aliquid fuel burner according to claim 12 or 13, characterized in thatthe inner cap is disposed eccentrically relative to the cap and asurface orthogonal to a direction of attachment/detachment at aperipheral fitting portion of the cap and the fuel tank is shaped tohave radial symmetry.
 17. A liquid fuel burner according to claim 10 or12, characterized in that an upper end of the fuel tank is providedabout at least part of its outer periphery with an upwardly projectingperipheral wall.
 18. A liquid fuel burner according to claim 10 or 12,characterized in that it comprises a guide member for slidingly guidingthe cap in the attachment/detachment direction relative to the fuel tankand further enabling the cap to move from over the wick and the igniterto a retracted position after it has moved to or beyond a position whereit disengages from the fuel tank.
 19. A liquid fuel burner according toclaim 18, characterized in that the guide member is constituted as ashaft member for guiding the cap in the attachment/detachment directionrelative to the fuel tank to a position where a lower end of the cap ishigher than tip portions of the wick and the igniter, the shaft memberbeing connected to the cap at a point apart from its center and the capbeing adapted to rotate to the retracted position about the shaftmember.
 20. A liquid fuel burner according to claim 18, characterized inthat the guide member is provided midway with a hinge and the cap ismovable to the retracted position by swinging in an upward arc about thehinge.
 21. A liquid fuel burner according to claim 18, characterized inthat energizing means is provided for biasing the cap from a slidposition on the guide member to the retracted position.
 22. A liquidfuel burner according to any of claims 10 to 13 wherein the wick isdivided into two segments at least one of which is movable to contactand separate from the other, fuel being supplied from one segment to theother during contact and fuel supply being cut off during separation.